Drugs / Letrozole
Letrozole
DrugLetrozole is an aromatase inhibitor and antiestrogen used mainly for hormone receptor-positive breast cancer in postmenopausal women. It is marketed under the brand name Femara and used in adjuvant, extended adjuvant, and advanced disease settings. The U.S. approval history begins in the 1990s.
- Trials
- 670
- Recruiting
- 87
- Completed
- 304
- With results
- 165
Last revised
Pipeline
Phase by status
| Phase | Recruiting | Not yet | By invitation | Active | Completed | Terminated | Withdrawn | Suspended | Unknown | No longer available | Total |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Early Phase 1 | 2 | — | — | — | 7 | 2 | 2 | — | 1 | — | 14 |
| Phase 1 | 6 | — | — | 5 | 30 | 5 | 4 | — | 2 | — | 52 |
| Phase 1/2 | 9 | 2 | — | 3 | 11 | 2 | 1 | — | 7 | — | 35 |
| Phase 2 | 32 | 11 | 1 | 30 | 104 | 32 | 5 | — | 29 | — | 244 |
| Phase 2/3 | 3 | — | — | 2 | 13 | 2 | — | — | 4 | — | 24 |
| Phase 3 | 22 | 3 | 1 | 23 | 58 | 10 | 2 | 1 | 20 | — | 140 |
| Phase 4 | 4 | 1 | — | 2 | 27 | 7 | 5 | — | 12 | — | 58 |
| Not applicable | 7 | 4 | — | 1 | 37 | 2 | 2 | — | 16 | — | 69 |
| Unknown | 2 | 2 | — | 1 | 17 | — | — | — | 11 | 1 | 34 |
Trials started per year
Conditions studied, by phase
| Condition | Early Phase 1 | Phase 1 | Phase 1/2 | Phase 2 | Phase 2/3 | Phase 3 | Phase 4 | Not applicable | Unknown | Total |
|---|---|---|---|---|---|---|---|---|---|---|
| Breast Neoplasms | 7 | 28 | 22 | 168 | 6 | 92 | 20 | 12 | 26 | 381 |
| Polycystic Ovary Syndrome | — | 3 | — | 2 | 2 | 11 | 6 | 15 | 2 | 41 |
| Infertility | 1 | — | — | 1 | 3 | 12 | 8 | 9 | — | 34 |
| Neoplasm Metastasis | — | 5 | — | 4 | 1 | 7 | 2 | 2 | 2 | 23 |
| Endometrial Neoplasms | — | — | 3 | 13 | 4 | 1 | — | 1 | — | 22 |
| Ovarian Neoplasms | 2 | — | 1 | 11 | — | 1 | — | — | — | 15 |
| Neoplasms | — | 2 | 1 | 4 | — | 3 | — | 1 | 3 | 14 |
| Carcinoma, Intraductal, Noninfiltrating | — | 1 | 1 | 4 | — | 2 | — | — | 1 | 9 |
| Infertility, Female | — | 1 | — | — | — | 2 | 2 | 4 | — | 9 |
| Fallopian Tube Neoplasms | — | — | 1 | 5 | — | 2 | — | — | — | 8 |
Most active sponsors
| # | Sponsor | Trials | Phase 3 |
|---|---|---|---|
| 1 | Novartis Pharmaceuticals | 46 | 17 |
| 2 | Pfizer | 21 | 5 |
| 3 | Fudan University | 12 | 6 |
| 4 | M.D. Anderson Cancer Center | 11 | 0 |
| 5 | Cairo University | 10 | 3 |
| 6 | Dana-Farber Cancer Institute | 10 | 0 |
| 7 | Assiut University | 9 | 3 |
| 8 | Eli Lilly and Company | 9 | 4 |
| 9 | Mayo Clinic | 8 | 0 |
| 10 | University of Washington | 8 | 0 |
Most studied interventions
| # | Intervention | Trials |
|---|---|---|
| 1 | Letrozole | 670 |
| 2 | Anastrozole | 157 |
| 3 | exemestane | 119 |
| 4 | Tamoxifen | 97 |
| 5 | Fulvestrant | 94 |
| 6 | palbociclib | 83 |
| 7 | ribociclib | 52 |
| 8 | abemaciclib | 44 |
| 9 | Aromatase Inhibitors | 43 |
| 10 | Trastuzumab | 41 |
Evidence
- Results reported
- 54.3%165 of 304 completed
- Published
- 16.8%51 of 304 completed
- Primary endpoint met
- 57.4%35 of 61 analyses
- Median months to report
- 14
Documents disclosed
Trial profile
- Median enrollment
- 100
- Median duration
- 51months
- Countries
- 79
- Study sites
- 12772
Who is enrolled
Median enrollment by phase
- Early Phase 1
- 27
- Phase 1
- 44
- Phase 1/2
- 79
- Phase 2
- 65
- Phase 2/3
- 66
- Phase 3
- 423
- Phase 4
- 100
- Not applicable
- 80
- Unknown
- 200
Where trials run
Busiest cities
| # | City | Country | Trials |
|---|---|---|---|
| 1 | Boston | United States | 76 |
| 2 | Houston | United States | 76 |
| 3 | New York | United States | 70 |
| 4 | Madrid | Spain | 63 |
| 5 | Barcelona | Spain | 61 |
| 6 | Nashville | United States | 58 |
| 7 | Seoul | South Korea | 52 |
| 8 | Valencia | Spain | 52 |
| 9 | Los Angeles | United States | 50 |
| 10 | Chicago | United States | 49 |
Terminations
- Terminated
- 62
- Withdrawn
- 21
- Suspended
- 1
- Stopped for recruitment
- 4.3%29 of 670 trials
Stated reasons
Reasons are grouped from the sponsor's own wording with a rule-based classifier; the original text is shown below.
Recently stopped
| Trial | Status | Stated reason | Stopped |
|---|---|---|---|
| NCT06671912 Suspended | Suspended | Amending protocol to increase sample size | 2031-11-30 |
| NCT07570966 Withdrawn | Withdrawn | Business decision | 2031-08-01 |
| NCT04220476 Withdrawn | Withdrawn | Initiating a new study with revised Statistics. | 2028-12-31 |
| NCT04321551 Withdrawn | Withdrawn | study not funded in previous iteration. new clinicaltrials.gov protocol submitted for funded version of study | 2028-12-31 |
| NCT04316169 Withdrawn | Withdrawn | Funding and PI leaving institution | 2028-01-31 |
| NCT05238831 Withdrawn | Withdrawn | Withdrawn due to a change in therapeutic interventions. | 2026-05-31 |
| NCT05183828 Terminated | Terminated | Study ended earlier than anticipated due to end of funding. | 2026-05-13 |
| NCT05207709 Terminated | Terminated | The study was prematurely halted because enrollment was significantly delayed compared with the original projections due to the evolving therapeutic landscape. | 2026-03-26 |
| NCT06630325 Terminated | Terminated | Loss of support. | 2026-03-11 |
| NCT05454358 Terminated | Terminated | No enough participants | 2025-12-01 |
Trial records
Individual study records live on ClinicalTrials.gov. A sample of the trials counted above: